1. Field of the Invention
The invention relates to a process for joining a tube, such as either a finned/enhanced tube or a prime/smooth surface tube, to at least one baffle, support, and/or tube sheet in the manufacture or maintenance of a tubular heat transfer system that uses an electromagnetic force to expand the tubes such that the outer surface of the tubes makes joining contact with apertures in the sheets.
2. Description of the Related Art
Tubular heat transfer systems include tubular systems of the type conventionally employed in air conditioners, heat exchangers, chillers, evaporators, boilers, and absorption units. The efficiency of tubular heat transfer systems is dependent in substantial measure on the efficiency of heat transferred between a media circulated through tubes and another media in heat exchange relation to the exterior of the tubes. The efficiency of heat transferred between the fluid surrounding the tubes is also enhanced by avoiding laminar flow of the fluid over the tubes.
The tubes used in a tubular heat transfer system are held in place by tube sheets situated on the end of the tubular heat transfer system. One or more tube supports sheets or baffle sheets may be provided to support the tubes between the tube sheets. Tubular heat transfer system tubes are supplied in various surface configurations that enable certain media to exchange heat better than others. The expander referenced here will expand either prime/smooth tubes or enhanced/finned tubes. Enhanced tubes are manufactured with a variety of inside surface raised ridges to provide turbulence to the flow through the tube, which enables greater heat transfer. Finned tubes are also manufactured with a variety of fin configurations on the outside surface and are selected based on the media that is being used to transfer heat over the tubes. Because of these two surface configurations, current tube expanders are unable to adequately expand these enhanced/finned tubes. Conventionally inside surface enhancing and outside surface finning are suspended in areas where the tube is to be joined to the support/baffle sheets and the end tube sheets because conventional tube expanders destroy internal ridges and overwork the tube and produce stress cracking at the junctions between the tube and the support/baffle sheets. In general, the ability to expand a tube is dependent on three conditions, the tube's thickness, diameter and the material the tube is made from.
U.S. Pat. No. 5,050,669 discloses a tube support which includes at least two parallel plates. The plates comprise a plurality of pins that approximate the leading and trailing edges of the plates in order to maintain the plates in a spaced relationship. The pins and plates provide support for the tubes. The use of electromagnetic force to expand a tube is described in U.S. Pat. No. 5,853,507 to Alie et al.; U.S. Pat. No. 6,050,121 to Daehn et al.; U.S. Pat. No. 4,947,667 to Gunkel et al.; U.S. Pat. No. 5,457,977 to Wilson; U.S. Pat. No. 4,924,584 to Hamey; U.S. Pat. No. 4,059,882 to Wunder; U.S. Pat. No. 6,273,963 to Barber U.S. Pat. No. 4.929,415 to Okaziki; U.S. Pat. No. 4,975,412 to Okaziki; U.S. Pat. No. 5,405,574 to Chelluri at al.;
If the intersection or joint between the tubes and tube sheets or baffle sheets is not tight, fluid can leak from the heat exchanger shell over time. Also, if the intersection or joint between the tube and baffle or support sheets is not tight, fluid flow will cause vibration between the tube and baffle or support sheet that can lead to undesirable wearing of the tube at the interface. Over time this wearing can lead to premature failure of the tube.
There is, therefore, a need for a tubular heat transfer system manufacturing system and method for securing a plurality of tubes to any surrounding members, such as support plates, end plates or baffle plates which improves the securing of the tubes to the sheets and which can be used to join enhanced or finned tubes without damaging the tube.